Function
α-Galactosidase (Agal) hydrolyzes the terminal α-galactosyl moiety from glycoproteins and glycolipids[1]. β-Galactosidase (Bgal) hydrolyzes β-galactosides into monosaccharides[2].
Isopropyl-β-d-thiogalactopyranoside (IPTG) induces Bgal activity. Phenylethyl-β-d-thiogalactopyranoside (PETG) is an inhibitor. Galactose, lactose, o-nitrophenyl-β-d-galactoside (ONPG) are substrates. Galactopyranosyl is reaction intermediate. For details on β-galactosidase see Molecular Playground/Beta-galactosidase.
Relevance
Bgal assay is used in molecular biology to monitor gene expression.
Disease
The inherited deficiency of Agal is the cause of Fabry disease[3]. Bgal mutations causing enzyme deficiency can lead to ganglioidosis[4].
Structural highlights
The Zn+2 binding site is composed of 4 Cys residues. The galactose binding site is seen in a large central channel[5]. For 3hg2 .
3D Structures of Galactosidase
Updated on 03-March-2016
References
- ↑ Garman SC, Garboczi DN. The molecular defect leading to Fabry disease: structure of human alpha-galactosidase. J Mol Biol. 2004 Mar 19;337(2):319-35. PMID:15003450 doi:10.1016/j.jmb.2004.01.035
- ↑ Jacobson RH, Zhang XJ, DuBose RF, Matthews BW. Three-dimensional structure of beta-galactosidase from E. coli. Nature. 1994 Jun 30;369(6483):761-6. PMID:8008071 doi:http://dx.doi.org/10.1038/369761a08015589
- ↑ Kint JA. Fabry's disease: alpha-galactosidase deficiency. Science. 1970 Feb 27;167(3922):1268-9. PMID:5411915
- ↑ Morrone A, Bardelli T, Donati MA, Giorgi M, Di Rocco M, Gatti R, Parini R, Ricci R, Taddeucci G, D'Azzo A, Zammarchi E. beta-galactosidase gene mutations affecting the lysosomal enzyme and the elastin-binding protein in GM1-gangliosidosis patients with cardiac involvement. Hum Mutat. 2000;15(4):354-66. PMID:10737981 doi:<354::AID-HUMU8>3.0.CO;2-L 10.1002/(SICI)1098-1004(200004)15:4<354::AID-HUMU8>3.0.CO;2-L
- ↑ Hidaka M, Fushinobu S, Ohtsu N, Motoshima H, Matsuzawa H, Shoun H, Wakagi T. Trimeric crystal structure of the glycoside hydrolase family 42 beta-galactosidase from Thermus thermophilus A4 and the structure of its complex with galactose. J Mol Biol. 2002 Sep 6;322(1):79-91. PMID:12215416
